Axillary Nerve

Question 1

Nerve roots and origin?

Answer 1

c5- c6

posterior cord of brachial plexus

formed from posterior division of upper trunk

Question 2

Nerve course?

Answer 2

it passes beneath the shoulder joint through the quadrangular space with the posterior circumflex humeral artery

it then wraps around the surgical neck of the humerus

Question 3

Sensory supply?

Answer 3

the “sergeant’s patch” of skin over the lower part of deltoid muscle (numbness)

Question 4

Features of nerve palsy?

Answer 4

MOTOR DEFICIT
paralysis of deltoid – very weak shoulder abduction from 15-90°; weak shoulder flexion and extension

paralysis of teres minor – weak shoulder external rotation

DEFORMITY
wasting of deltoid muscle, making the bones of the shoulder joint very prominent and obvious
shoulder may appear adducted and internally rotated